|Year : 2014 | Volume
| Issue : 2 | Page : 143-145
Hammock mitral valve: A rare case report
Veeresh F. Manvi1, M. D. Dixit2, Srinivas M. Kini2, Nidhi Goel Manvi2, Anand Vagrali3, Sharan Patil3
1 Department of Pediatric Cardiology, KLES Dr. P. K. Hospital and Medical Research Centre, Belgaum, Karnataka, India
2 Department of Cardiothoracic Vascular Surgery, KLES Dr. P. K. Hospital and Medical Research Centre, Belgaum, Karnataka, India
3 Department of Cardiac Anesthesia, KLES Dr. P. K. Hospital and Medical Research Centre, Belgaum, Karnataka, India
|Date of Web Publication||20-May-2014|
Veeresh F. Manvi
Department of Pediatric Cardiology, KLES Dr. P. K. Hospital and Medical Research Centre, Department of Pediatrics, JNMC, Belgaum - 590 010, Karnataka
Source of Support: None, Conflict of Interest: None
Congenital mitral stenosis is a relatively rare disorder comprising 0.2% of all congenital heart defects. Hammock mitral valve producing severe mitral stenosis is a rare variant of congenital mitral stenosis. We report a 2-year-old boy who had hammock mitral valve producing severe mitral stenosis with severe pulmonary artery hypertension. He underwent successful surgical repair. Post-surgery, the mitral valve opening was adequate without residual stenosis or regurgitation. Pulmonary artery pressure had normalized. Follow-up data showed he had significant clinical and echocardiography improvement. This is the first reported case of successful surgical repair done for hammock mitral valve from our institute.
Keywords: Congenital, hammock mitral valve, mitral stenosis, pulmonary artery hypertension, surgical repair
|How to cite this article:|
Manvi VF, Dixit MD, Kini SM, Manvi NG, Vagrali A, Patil S. Hammock mitral valve: A rare case report. J Sci Soc 2014;41:143-5
| Introduction|| |
Congenital mitral valve stenosis, a rare entity and takes several forms.  These include hypoplasia of the mitral valve annulus, mitral valve commissural fusion, double orifice mitral valve, shortened or thickened chordae tendinae, hammock mitral valve and parachute mitral valve in which all chordae attach to a single papillary muscle.  Congenital MS is usually detected in infancy if mitral stenosis is severe enough to produce physical findings or to provoke overt symptoms. Management of congenital mitral valve disease is challenging because of a wide morphologic spectrum, frequent associated lesions and small patient size. Hammock mitral valve repair is a highly challenging procedure, particularly in infants and small children. The greatest degree of leaflet mobility must be restored in order to prevent tethering. Surgical repair of the congenital mitral valve can be successfully performed with low mortality and satisfactory valve function. Suboptimal primary repair is a significant predictor for reoperation.
| Case report|| |
A 2-year old boy weighing 6 kg presented to us with symptoms of frequent respiratory tract infection. He was evaluated by a pediatrician who suspected him to have congenital heart disease and referred to our center. On detailed evaluation, it was found that the child had severe breathlessness, feeding difficulty, failure to thrive and recurrent respiratory tract infection. On examination, the child had signs of congestive heart failure. Precordial bulge was present. There were precordial pulsations, grade III parasternal heave and right ventricular type of apical impulse. On auscultation, there was a loud second heart sound, which was narrowly split. A rough rumbling mid diastolic murmur was heard. Chest radiograph showed cardiomegaly with prominent pulmonary artery and left atrial shadows. Electrocardiography showed left atrial dilatation with prominent right ventricular forces.
Echocardiography showed severe congenital mitral valve stenosis. The mitral valve annulus was normal in size (15 mm, Z score = 0.1). The chordae tendinae of posterior mitral leaflet were short in length. They were inserted into a rudimentary and hypoplastic posteromedial papillary muscle. The anterior leaflet was normal in size and its chordae were attached normally into the anterolateral papillary muscle. Commissural fusion was noticed. Mean gradient across the mitral valve was 18 mmHg. There was no mitral regurgitation. Mitral valve orifice area was 0.9 cm 2 . The left atrium was hugely dilated. There was severe pulmonary artery hypertension as assessed by tricuspid valve regurgitation peak gradient of 105 mmHg. Right ventricle was hypertrophied. No other associated anomalies were noted.
Surgical repair of congenital mitral stenosis was indicated and patient was taken up for mitral valve repair. Intraoperative surgical findings were suggestive of hammock mitral valve. The chordae tendinae of posterior mitral leaflet were short, thick and hypoplastic. They were partly attached to hypoplastic posterior medial papillary muscle and partly attached directly to the posterior wall of the left ventricle.
The anterior lateral papillary muscle was spilt sagittally. An interposing strip of pericardium was placed between the split ends. Valve was tested for competency and was found to be adequate. The cardiopulmonary bypass time was 69 min and cross-clamp time was 47 min. Patient came off cardiopulmonary bypass uneventfully. Epicardial echo done intraoperatively showed well opened mitral valve with laminar flow. The mean gradient across the mitral valve had significantly reduced to 4 mmHg. The pulmonary artery systolic pressure had reduced to 48 mmHg. Child was extubated next day morning and had an uneventful post-operative stay. Child was discharged after 6 days with decongestive therapy.
After 1 month, follow-up showed normally functioning mitral valve with no mitral regurgitation. There was a further reduction in pulmonary artery pressure. Child had become asymptomatic and had gained weight.
| Discussion|| |
Isolated congenital mitral valve disease is uncommon, occurring in approximately four per thousand children with congenital heart disease. , A comprehensive description of mitral valve anatomy and function of its components is necessary to appreciate the pathophysiologic and clinical manifestations of the diseases of mitral valve and their management in children. The valve is very complex three-dimensional assembly of separate anatomic components, including the annulus, the leaflets and commissures, the chordae, the papillary muscles and the ventricle. , These individual components function in an integrated manner to provide unobstructed diastolic flow of pulmonary venous blood into the left ventricle and to maintain a competent seal of the inlet during systole. Functional obstruction of the mitral valve apparatus impairs pulmonary venous flow from the left atrium into the left ventricle. Consequently, the left atrial, pulmonary venous and capillary pressure rises. This leads to chronically elevated pulmonary artery pressure and secondary right ventricle dysfunction. 
Most cases of congenital mitral stenosis involve diffuse abnormalities of the valve components. A variable combination of anomalies can occur, including thickened, rolled leaflet margins, shortened and thickened chordae tendineae, fibrous obliteration of the interchordal spaces, abnormal chordal insertions, papillary muscle hypoplasia and decreased inter papillary muscle distance. ,
A rare variant of congenital mitral stenosis is hammock valve, also known as mitral arcade. ,, The mitral valve leaflets are thickened and chordae are markedly shortened. The leaflets appear to insert directly into the papillary muscle or posterior ventricular wall resulting in constrained mitral valve excursion. An abnormal band of fibrous tissue often extends along the free margin of one or both leaflets, thus tethering the leaflet and papillary muscle, resulting in restriction of mitral valve orifice area. Reduced leaflet coaptation may be associated with insufficiency as well.
Successful surgical management requires long-term planning, careful assessment of clinical and hemodynamic severity.  The prognosis for successful surgical management is related to patient's age, size, severity of mitral valve obstruction, annular hypoplasia, ventricular size, severity of pulmonary artery hypertension and presence of accompanying lesions. Uva et al. reported no operative mortality for valve reconstruction in 19 infants, but freedom from reoperation was disappointingly low being 58% at 7 years.  In contrast, Brauner et al. reported total mortality of 26% in a mitral group requiring replacement or repair.  Carpentier developed surgical techniques that have revolutionized the surgery of congenital mitral valve stenosis, which include annulus remodeling, leaflet resection, chordal shortening and chordal fenestration. 
This is the first reported case of successful surgical repair done for hammock mitral valve from our institute.
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